Our egress pricing (from all sources) is certainly higher because we operate a private backbone rather than just dumping your packets straight onto the internet.
Your site seems to be hugged to death (so I can't see it), but there are lots of gotchas with S3 pricing (like rounding up file sizes with Infrequent Access and Glacier) that in our experience means our customers come out ahead. Glacier and Coldline also aren't really comparable in the sense that GCS always responds within milliseconds. We only economics to discourage frequent access from Coldline, not delays. As above, our egress is more expensive because it's better (we hear you though if your response is "I don't care! Give me cheaper instead, then!").
Your site seems to be hugged to death (so I can't see it), but there are lots of gotchas with S3 pricing (like rounding up file sizes with Infrequent Access and Glacier) that in our experience means our customers come out ahead. Glacier and Coldline also aren't really comparable in the sense that GCS always responds within milliseconds. We only economics to discourage frequent access from Coldline, not delays. As above, our egress is more expensive because it's better (we hear you though if your response is "I don't care! Give me cheaper instead, then!").
Disclosure: I work on Google Cloud.